A constant delivery micropump using surface tension and thermopneumatic pressure

This paper presents the fabrication and test of a constant delivery thermopneumatic micropump made of PDMS without any moving part. The driving force of the liquid discharge is the pneumatic pressure of heated air and the suction of liquid is accomplished by the surface tension. The proposed micropump consists of an inlet, an outlet, a pump chamber, two air chambers, two air discharge channels and two air suction channels. The air chambers have electric heaters on the Pyrex glass substrate. Each air chamber is connected the pump chamber through two different air channels which behaves like check valves. The micropump is fabricated through the spincoating process, the lithograph process, the PDMS molding process and etc. The total dimension of the micropump is 11.7 × 8.8 × 0.7 mm³. The discharge volume of the fabricated micropump was measured for various backward pressures ranging from 0 to 20 cmH₂O. The micropump discharges 116 nanoliters in 4 seconds for zero discharge pressure when the input voltage is 3.5 V. As the discharge pressure increases, the discharge volume decreases gradually. The discharge volume deviation is less than 15 percent for the discharge pressure range between 5 and 15 cmH₂O. This proposed micropump is feasible for disposable transdermal drug delivery systems.